Herd immunity: cow virus successfully targeted for extinction

The campaign may have lessons well beyond livestock.

Mankind has caused no end of accidental extinctions, but there's one intentional one that we're rightly proud of: smallpox, which no longer circulates in the human population. But last year, humanity celebrated a similar success, eliminating another virus from the wild. It just didn't get as much attention because the virus in question targeted cattle. But, for those whose livelihoods depend on cattle, this was a major advance. And, according to a review of its eradication published in Science, our ability to wipe it out in a few remaining pockets of Africa may have important lessons for other diseases, including those that infect humans.

The virus in question, a relative of the measles virus, causes a disease called rinderpest. If it isn't familiar, that may be because it was such a problem that control efforts in Europe date back as far as the 1600s. Use of vaccines against it date back to the 1800s (and, the article helpfully points out, rinderpest control was the target of the first rectal thermometers). As a result, the virus has been largely in check in Europe.

But in the late 1800s, it made the jump to Africa, and the results explain why eliminating the virus is such a triumph: the paper cites a 90 percent mortality as the virus spread through the continent. That's also why it's generally been considered the animal disease that has the largest impact on human well-being.

Out of Africa

The vaccinations and control strategies that worked well in many parts of Europe also limited rinderpest in some parts of Africa. By the 1980s, the international groups and the governments of Africa attempted a continent-wide vaccination campaign, which severely limited the presence of the virus, confining it primarily to a remote area of Uganda and unstable areas in the Horn of Africa, such as Sudan and Somalia and their neighbors. By 1990, Ethiopia was using 21 million doses of vaccine in an attempt to wipe out the last pockets of the virus.

At that point, animal health authorities began to worry that "The eradication effort was drifting toward indefinite disease containment of remote endemic areas, with donor fatigue looming on the horizon." A fundamental rethink seemed to be required.

Fortunately, some of the pieces were already in place. In the 1980s, a vaccine that could maintain potency without refrigeration was identified as a research priority. In only four years, the animal health community had one that could go without refrigeration for at least a month.

Meanwhile, studies of the virus itself had provided some measures of the efficiency of its spread, and the size of unvaccinated populations needed for it to maintain itself in the wild. Key measures like the number of infections that result from each infected animal suggested that a herd immunity level of 80 percent immunity would be enough to wipe the virus out.

In areas with limited infrastructure and government, however, getting to that level of vaccination was going to be a challenge. So, the eradication program decided to forgo the usual infrastructure and train the animal equivalent of community health workers. These would both report on outbreaks of the disease, and help get vaccine to the remote regions and administer it there. To gain acceptance from the local communities, the local veterinary experts (both trained and informal) had to be assured that these new workers were not a threat to their livelihood.

With the new plan in place, Ethiopia went from administering 20 million doses down to doing 3 million annually, but targeting them to the areas where they would disrupt transmission of the disease and eradicate reservoirs. In Somalia, total immunity probably didn't get much above half but, with careful targeting, that was enough.

Lessons for other diseases

Two factors were essential for the elimination of rinderpest: the relatively low rate at which infections spread from a single animal, and the fact that African cattle have an average lifespan of five years, which allows a single vaccination to have an extended benefit. The high rate of mortality also ensured that there was a high interest in getting rid of the disease.

These are not likely to be easily met with other diseases. Domestic poultry are too numerous, and have a very short life span on average; goats and sheep are marginal. Meanwhile, foot-and-mouth disease has a very high rate of infection that means that herd immunity needs to be well above 90 percent to prevent transmission. It's also not as lethal, which means that indigenous farmers are more likely to accept it as an occasional hazard.

The success with rinderpest may also have a lesson for those trying to wipe out human diseases. It is possible to run a successful vaccine campaign in areas with limited infrastructure and government. But that success will rely on local cooperation, both in terms of people willing to monitor and report the spread of the disease, and in terms of cooperating with those administering the vaccine. Recruiting local health workers for vaccine administration is also likely to be essential.

All of that assumes a that the local population has bought into the need for the vaccine. And, at least in the case of the human disease closest to eradication, polio, that has become a serious problem, as many local figures in the last remaining pockets have linked the vaccine to various conspiracies.

Setting aside religious objections to vaccination for a minute, I believe the most efficient way to mass vaccinate is via an airborne vaccine - eliminates the task of bringing people into clinics entirely. Of course, that leaves the window open to the vaccine being weaponized though.

Great news - now we just have to vaccinate against stupidity and we can eradicate polio, mumps, rubella... maybe even HPV.

Clearly the cows didn't have any religious problems with the concept of vaccination, either.

Is there a large religious problem with the concept of vaccination? Certainly not in the states, I think. The biggest problem seems to be ignorant parents that think their kids are better off not getting vaccinated for a host of nonsense reasons, including fear of autism.

Personally, I feel that if you refuse to vaccinate your child and someone, often another child, is injured or killed because your child spread disease you should be criminally and civilly liable.

Unfortunately, we have no vaccine against stupidity and herd immunity seems nonexistent for that most serious of maladies.

Great news - now we just have to vaccinate against stupidity and we can eradicate polio, mumps, rubella... maybe even HPV.

Clearly the cows didn't have any religious problems with the concept of vaccination, either.

Is there a large religious problem with the concept of vaccination? Certainly not in the states, I think. The biggest problem seems to be ignorant parents that think their kids are better off not getting vaccinated for a host of nonsense reasons, including fear of autism.

Personally, I feel that if you refuse to vaccinate your child and someone, often another child, is injured or killed because your child spread disease you should be criminally and civilly liable.

Unfortunately, we have no vaccine against stupidity and herd immunity seems nonexistent for that most serious of maladies.

GAAaaaa..... My sister in law is one of those. No amount of logic, science, math, or debunking will change her mind. Even though the doctor that started that all has since been disbarred she still will not vaccinate her kids. Granted it's her decision, but she can't grasp the larger picture as statistics and 'thinking outside the box' are beyond her.

I don't know if there are enough antivaxers in the Ars community to support a large outbreak in this thread. Yay herd immunity!

I'm not against vaccinations, but I am thoroughly amused at how the scientific egoists here view this evidence. The disease control people stopped blanket immunization (which weren't working) and used dramatically fewer, but targeted immunizations to effectively eradicate the virus. Yet, people are acting as through it is evidence FOR blanket immunizations.

To claim that this article is pro-blanket immunizations is no less absurd than claiming that intelligent usage of vaccinations is not wise.

(I wait for the day when people stop pointing to other idiots to justify their own equally wrong opinions - just opinions on the other side of the pendulum swing.)

Setting aside religious objections to vaccination for a minute, I believe the most efficient way to mass vaccinate is via an airborne vaccine - eliminates the task of bringing people into clinics entirely. Of course, that leaves the window open to the vaccine being weaponized though.

A few problems with air delivery:1) Many diseases can't be cured this way. 2) If you have a transient population, you have to spray repeatedly, which is a lot more complicated than setting up a single checkpoint on a road.3) It has to be a VERY safe vaccine. If even .1% of the population reacts violently to the vaccine, you can't do it. Particularly if the population is vaccine-averse. Imagine the uproar if a dozen people die in a Pakistani town of 10,000 in the day after a spraying.

Weaponization really has nothing to do with this. Bioweapons, like many WMD's aren't so complex that a third world country couldn't build them. The reason why even Iran, Syria and the DPRK don't use bioweapons (Iraq was probably the last country with a big program, but it was shuttered after the Gulf War) because they're highly unpredictable. There's no way to stop it from infecting your people. Terrorists don't use them, because, honestly, they're not that smart. Al Qaeda doesn't have labs. They spend more time fetishing about airplanes than it would take to build 10 suicide vests, find 10 idiots, and send both into packed malls during the holidays.

Great news - now we just have to vaccinate against stupidity and we can eradicate polio, mumps, rubella... maybe even HPV.

Clearly the cows didn't have any religious problems with the concept of vaccination, either.

Is there a large religious problem with the concept of vaccination? Certainly not in the states, I think. The biggest problem seems to be ignorant parents that think their kids are better off not getting vaccinated for a host of nonsense reasons, including fear of autism.

Personally, I feel that if you refuse to vaccinate your child and someone, often another child, is injured or killed because your child spread disease you should be criminally and civilly liable.

Unfortunately, we have no vaccine against stupidity and herd immunity seems nonexistent for that most serious of maladies.

No there is not a large religious problem with the concept of vaccinations in the first world. This will not stop countless Ars anti-religion drones from posting as if it was the main problem. Religion, it appears, is the main cause of all maladies around here. It is the same behavior you see in any of the science stores about the universe. I don't know when the last time someone actually posted that really believed the earth was only 6000 years old, but in all of those threads hilarious individuals post as if they were true believers. Occasionally, the posts are funny, mostly they are just as stupid as the belief that the earth is only 6000 years old.

I'm not against vaccinations, but I am thoroughly amused at how the scientific egoists here view this evidence. The disease control people stopped blanket immunization (which weren't working) and used dramatically fewer, but targeted immunizations to effectively eradicate the virus. Yet, people are acting as through it is evidence FOR blanket immunizations.

I think that's oversimplifying the situation to the point of being naive. The reasons the virus was confined to the hinterlands were: 1) the easily accessible cattle were already vaccinated; 2) Other methods were used to control the contact between different populations of cattle, something that would be unacceptable in a human population; 3) the risk of some cattle eluding these controls was not catastrophic.

Could we stop vaccinating for polio in the US and simply target the areas (Pakistan, Nigeria) where it remains endemic, thereby using fewer vaccine doses? Yes, but only if you can guarantee that nobody from these areas will ever come in contact with an unvaccinated US citizen.

Because we can't, blanket immunizations remain far and away our best option.

I don't know if there are enough antivaxers in the Ars community to support a large outbreak in this thread. Yay herd immunity!

I'm not against vaccinations, but I am thoroughly amused at how the scientific egoists here view this evidence. The disease control people stopped blanket immunization (which weren't working) and used dramatically fewer, but targeted immunizations to effectively eradicate the virus. Yet, people are acting as through it is evidence FOR blanket immunizations.

To claim that this article is pro-blanket immunizations is no less absurd than claiming that intelligent usage of vaccinations is not wise.

(I wait for the day when people stop pointing to other idiots to justify their own equally wrong opinions - just opinions on the other side of the pendulum swing.)

Vaccination is fine and dandy so long as it is voluntary. Using the threat of violence to force vaccination is about as wrong as the government of china forcefully sterilizing its population due to overpopulation.

Vaccination is fine and dandy so long as it is voluntary. Using the threat of violence to force vaccination is about as wrong as the government of china forcefully sterilizing its population due to overpopulation.

Interesting view. So the .gov should take no action when people decide to engage in activities that will hurt or kill others?Would this mean that laws that are for the common good are not there to encourage people to do the right thing when they are inclined to do otherwise?As I drove past a Walgreens and saw them advertising that they had whooping cough vaccine in it was pretty clear that anti-vaxers have gotten to a large enough number to beat herd immunity in places and to successfully begin to kill other people's children along with their own.

Perhaps I am incorrect, but weren't a number of objections to the HPV vaccine from abstinence-only religious groups?

Yup. They'd rather have their daughters catch cervical cancer. See, sex is evil, I told you so!

Ah, no, one should not conflate moral objections, mistakenly IMHO, with religious belief. There's obviously a relationship, but they are not isomorphic. Neither is the implication of certain social side-effects of HPV applied to children imply a "religious problems with the concept of vaccination".

Resistance to vaccinations, conceptually, seems to more of an issue with the Oprah Winfrey crowd:

It's those damned redneck, religious, rightwing nuts in San Francisco that send their kids to private schools. Why don't they just shut the hell up with their anti-science...bah, blah, blah...FSM, blah, blah, blah, right? But, I don't expect facts to get in the way of your bigotry.

I am unapologetically, pro-vaccination. It's a public service to your fellow man to get vaccinated. I really feel strongly that those that don't get vaccinated or don't have their children vaccinated should face, at least, civil penalties--criminal, if someone is injured because of their ignorance and negligence.

Than again, this was supposed to be a SCIENCE article on the eradication of a bovine virus and its potential implications for fighting human disease...sigh.

Vaccination is fine and dandy so long as it is voluntary. Using the threat of violence to force vaccination is about as wrong as the government of china forcefully sterilizing its population due to overpopulation.

Interesting view. So the .gov should take no action when people decide to engage in activities that will hurt or kill others?Would this mean that laws that are for the common good are not there to encourage people to do the right thing when they are inclined to do otherwise?As I drove past a Walgreens and saw them advertising that they had whooping cough vaccine in it was pretty clear that anti-vaxers have gotten to a large enough number to beat herd immunity in places and to successfully begin to kill other people's children along with their own.

I'm not against vaccinations, but I am thoroughly amused at how the scientific egoists here view this evidence. The disease control people stopped blanket immunization (which weren't working) and used dramatically fewer, but targeted immunizations to effectively eradicate the virus. Yet, people are acting as through it is evidence FOR blanket immunizations.

I think that's oversimplifying the situation to the point of being naive. The reasons the virus was confined to the hinterlands were: 1) the easily accessible cattle were already vaccinated; 2) Other methods were used to control the contact between different populations of cattle, something that would be unacceptable in a human population; 3) the risk of some cattle eluding these controls was not catastrophic.

Could we stop vaccinating for polio in the US and simply target the areas (Pakistan, Nigeria) where it remains endemic, thereby using fewer vaccine doses? Yes, but only if you can guarantee that nobody from these areas will ever come in contact with an unvaccinated US citizen.

Because we can't, blanket immunizations remain far and away our best option.

Wait, help me out here. The main argument of the anti-anti-vaxers is that their decisions could not only lead to their child getting sick, but infecting another... anti-vaxer? Is this not known as natural selection?

Wait, help me out here. The main argument of the anti-anti-vaxers is that their decisions could not only lead to their child getting sick, but infecting another... anti-vaxer? Is this not known as natural selection?

You're correct, but an outbreak would still clog up emergency rooms and hospitals from what amounts to a highly preventable cause.

Although we seem not to have a problem pushing life forms that have never harmed us to extintion at a rate of higher than any time since an asteroid took out the dinosaurs. Oh wait, you can't make weapons out of them. <Cynic mode off>

Wait, help me out here. The main argument of the anti-anti-vaxers is that their decisions could not only lead to their child getting sick, but infecting another... anti-vaxer? Is this not known as natural selection?

The issue is that there are a small number of children who cannot get vaccinated. The anti-vaxers killing them is the problem.

Wait, help me out here. The main argument of the anti-anti-vaxers is that their decisions could not only lead to their child getting sick, but infecting another... anti-vaxer? Is this not known as natural selection?

You're correct, but an outbreak would still clog up emergency rooms and hospitals from what amounts to a highly preventable cause.

-- The U.S. has had more than 26,000 whooping cough cases so far this year, including-- more than 10,000 in children ages 7 to 10.

-- "The substantial majority of the cases are explained by this waning immunity," said Dr.-- William Schaffner, an infectious-disease specialist at Vanderbilt University.

-- [...]

-- Whooping cough, or pertussis, is a highly contagious bacterial disease that can strike -- people of any age but is most dangerous to children. Its name comes from the sound-- youngsters make as they gasp for breath.

[...]

-- But cases of whooping cough began to climb, sometimes topping 25,000 a year during-- the past decade. Also disturbing: The proportion of cases involving children ages 7 to -- 10 -- most of them vaccinated -- rose from less than 10 percent before 2006 to nearly-- 40 percent this year, according to the CDC.

What when the emergency rooms are clogged with children vaccinated against that disease?